This invention relates to an electrical rotary potentiometer having a rotary control knob mounted in a housing, a manipulation adjustment angle of which is larger than a resistor tap angle of the electrical rotary potentiometer.
German patent document (DE 36 31 056 A1), for example, discloses a rotary potentiometer having a resistive strip, wound in a main body, that is contacted by a tap member acting in a radial direction relative to a rotational axis.
In this rotary potentiometer, a moment of friction that occurs during rotation can be adjusted by a coaxial screw that screws into the main body to press against a rotating body. This screw serves various functions. It attaches the rotating body to the main body, it provides a necessary contact pressure for the desired moment of friction between the rotating body and the main body, and it provides mechanical mounting of the rotary potentiometer.
German patent document (DE 89 12 785 U1) discloses a tandem potentiometer in which a wiper is coupled via step-down gearing to a drive shaft such that a wiper, or tap, is adjusted by a smaller angle than an angle of the drive shaft. This makes possible a more sensitive adjustment of the potentiometer.
The step-down gearing includes a planet-wheel gear system, with the wiper referred to above being connected to a planet wheel located between gearing of the drive shaft and a stationary, concentric gear wheel.
It is an object of this invention to provide an inexpensively-produced rotary potentiometer having sensitive adjustment and an adjusting moment of friction that is substantially identical for each device made.